title: Benefit of early treatment with oseltamivir in hospitalized patients with documented 2009 influenza A (H1N1): retrospective cohort study.
abstract: BACKGROUND
  We assessed the association between early oseltamivir treatment and influenza complications in hospitalized patients.
  
  
  METHODS
  A retrospective cohort study, including adults with laboratory-confirmed 2009 influenza A (H1N1) in three hospitals in Israel, was performed between July 2009 and January 2010, when admission was limited to high-risk patients. We compared patients treated with oseltamivir early versus late (>48 h after symptom onset). We analysed risk factors for complications, defined as radiographic pneumonia, hypoxia, mechanical ventilation, intensive care unit admission, haemodynamic support or in-hospital death. Risk factors for complications on univariate analysis were entered into a multivariable logistic regression analysis. Odds ratios (ORs) with 95% confidence intervals (CI) are reported.
  
  
  RESULTS
  Four hundred and forty-nine inpatients treated with oseltamivir were included, 189 (42.1%) of whom were treated early. Influenza complications occurred significantly more frequently among patients treated late with oseltamivir [150/260 (57.7%) versus 67/189 (35.4%), P < 0.001]. Late oseltamivir remained significantly associated with complications in the adjusted analysis (OR 2.37, 95% CI 1.52-3.70). Other independent risk factors included dyspnoea, disease severity on admission, lower sodium and treatment at one hospital; rhinorrhoea was protective. In an analysis adjusted for the propensity for early treatment the association remained significant (OR 2.21, 95% CI 1.41-3.46). Initiation of oseltamivir >48 h after admission was associated with a higher rate of complications documented after admission (OR 4.09, 95% CI 1.55-10.80). Severe complications (excluding hypoxia and uncomplicated pneumonia) occurred more frequently with late oseltamivir (adjusted OR 3.28,95% CI 1.56-6.89).
  
  
  CONCLUSIONS
  Initiation of oseltamivir within 48 h of symptom onset was associated with fewer complications in patients hospitalized with 2009 influenza A (H1N1).
authors.affiliation: School of Public Health, Tel-Aviv University, Ramat Aviv, Israel.
authors.forename: Vered
authors.initials: V
authors.lastname: Hiba
authors.forename: Michal
authors.initials: M
authors.lastname: Chowers
authors.forename: Inbal
authors.initials: I
authors.lastname: Levi-Vinograd
authors.forename: Bina
authors.initials: B
authors.lastname: Rubinovitch
authors.forename: Leonard
authors.initials: L
authors.lastname: Leibovici
authors.forename: Mical
authors.initials: M
authors.lastname: Paul
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000998:Antiviral Agents / Q000008:administration & dosage*; D015331:Cohort Studies; D003422:Critical Care / Q000706:statistics & numerical data; D005260:Female; D006760:Hospitalization; D006801:Humans; D000860:Hypoxia / Q000517:prevention & control; D053118:Influenza A Virus, H1N1 Subtype / Q000302:isolation & purification; D007251:Influenza, Human / Q000150:complications* / Q000188:drug therapy* / Q000401:mortality / Q000821:virology; D007557:Israel; D008297:Male; D008875:Middle Aged; D053139:Oseltamivir / Q000008:administration & dosage*; D018410:Pneumonia, Bacterial / Q000517:prevention & control; D012121:Respiration, Artificial / Q000706:statistics & numerical data; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D000998:Antiviral Agents; D053139:Oseltamivir